The present invention relates to new compounds, to processes for the production of the new compounds and to cosmetic compositions containing the new compounds as an active ingredient.
In GB-A-2 050 825 there is described a skin cosmetic composition of the oil-in-water type, comprising an emulsifying agent, an oil and water, the emulsifying agent being composed of a) at least one specified glycyrrhizic compound and b) at least one water-soluble polysaccharide selected from pectin, karaya gum, locust bean gum and xanthan gum.
The polysaccharides used in GB-A-2,050,825 have certain disadvantages, namely that they contain acidic groups, rendering them sensitive to salt formation and/or variations in pH, as well as a lack of stability over an adequate temperature range.
In JP030167109 there is described a cosmetic material containing a xcex2-1,3-glucan having a mean molecular weight greater than 10xc3x97106. xcex2-1,3-glucans having a mean molecular weight greater than 10xc3x97106, however, are of poor aspect, and their molecular weight cannot be determined using the conventional light scattering method.
It has now been found that certain new scleroglucans are useful as active ingredients and as excipients in cosmetic compositions, without the disadvantages associated with the polysaccharides used in GB-A-2,050,825 or with the xcex2-1,3-glucans of JP030167109. Moreover, the scleroglucans used in the present compositions, on drying, form flexible films which, although insoluble in water, swell readily therein. This ability to form films represents an added advantage for the use of these scleroglucans in cosmetic formulations. Still further, the new scleroglucans have been found to exhibit valuable anti-inflammatory properties, rendering them valuable, for example, as active ingredients in after-sun preparations for the treatment of sun burn.
Accordingly, the present invention provides, as a first aspect, a cosmetic composition comprising:
A) a cosmetically acceptable carrier; and
B) 0.05 to 3.0, preferably 0.2 to 1.0% by weight, based on the weight of the total composition, of a xcex2-1,3-scleroglucan having a three-dimensional crosslinked triple helix structure and having a mean molecular weight of 1xc3x97106 to 12xc3x97106, preferably 2xc3x97106 to 10xc3x97106.
The cosmetic composition may constitute, e.g., a shampoo and/or hair conditioner composition, in which the scleroglucan component B) may perform one or more of the following functions:
i) effect an improvement in the combability of hair treated with the shampoo/conditioner;
ii) effect an improvement in the dispersion of other components in the shampoo/conditioner;
iii) act as a smoothing agent for hair treated with the shampoo/conditioner; and
iv) effect an improvement in the level of fixing of such additives as dyes or UV absorbers in the shampoo/conditioner.
The cosmetic composition according to the present invention may also constitute a skin care composition, e.g., an emulsion or cream in which the scleroglucan may perform one or more of the following functions:
i) effect a lubricating function, thereby facilitating the spreading of the composition on the skin;
ii) act as a film-forming agent, thereby providing a protective film on the skin, which film, while almost undetectable by touching, provides the skin with a silky feel;
iii) effect a smoothing of the skin by reducing the scaling of the outermost layer of stratum corneum;
iv) effect an anti-inflammatory effect on the skin;
v) effect an improvement in the dispersion of other components of the skin care composition; and
vi) act as an emulsifier or co-emulsifier for the skin care composition.
The skin care composition may be formulated as an aqueous lotion, a water-in-oil or an oil-in-water emulsion, an oil or oil-alcohol lotion, a vesicular dispersion of anionic or nonionic amphiphilic lipids, an aqueous, aqueous-alcohol, alcohol or oil-alcohol gel, a solid stick or an aerosol formulation.
When formulated as a water-in-oil or an oil-in-water emulsion, the cosmetically acceptable carrier A) preferably comprises 5 to 50% of an oil phase; and 47 to 94.95% of water, each based on the total weight of the composition.
The oil phase may comprise any oil, or mixture thereof, which is known to be suitable for use in cosmetic compositions.
Examples of such oils include aliphatic hydrocarbons such as liquid paraffin, squalane, vaseline and ceresin; vegetable oils such as olive oil, almond oil, sesame oil, avocado oil, castor oil, cacao butter and palm oil; animal oils such shark liver oil, cod liver oil, whale oil, beef tallow and butter fat; waxes including bees wax, carnauba wax, spermaceti and lanolin; fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and behenic acid; aliphatic alcohols such as lauryl alcohol, stearyl alcohol, cetyl alcohol and oleyl alcohol; and aliphatic esters such as isopropyl-, isocetyl- or octadecyl myristate, butyl stearate, hexyl laurate, diisopropyl adipate or diisopropyl sebacate.
Preferred mono- or polyols, for use in an oil-alcohol lotion, or a an oil-alcohol or alcohol gel, include ethanol, isopropanol, propylene glycol, hexylene glycol, glycerine and sorbitol.
When the xcex2-1,3-scleroglucan is used as a co-emulsifier, the other emulsifier used may be any emulsifier conventionally used in cosmetic formulations e.g., one or more of an ethoxylated ester of a natural oil derivative such as a polyethoxylated ester of hydrogenated castor oil; a silicone oil emulsifier such as a silicone polyol; an optionally ethoxylated fatty acid soap; an ethoxylated fatty alcohol; an optionally ethoxylated sorbitan ester; an ethoxylated fatty acid; or an ethoxylated glyceride.
The cosmetic composition according to the present invention may constitute an anti-inflammatory skin care preparation, especially an after-sun skin care preparation.
The cosmetic composition according to the present invention may also constitute an oral care preparation, e.g., a dental gel, a denture fixation aid or a tooth paste; a mucosal lubricant formulation such as a vaginal cream or gel; or an ophthalmological preparation such as eye drops; in which the glucan component B) may perform one or more of the following functions:
i) effect lubrication of dry mucosae;
ii) effect thickening of liquid preparations;
iii) effect retention of active ingredients by formation of films on mucosal surfaces; and
iv) effect an improvement in the dispersion of other components in the composition.
When the xcex2-1,3-scleroglucan is used in an ophthalmological preparation, it may be used together with other components such as:
a) ophthalmological active ingredients e.g. Gentamicin sulphate, Lomefloxacin hydrochloride, Chloramphenicol, Sodium Diclofenac, Potassium Diclofenac, Dexamethason di-sodium phosphate, Naphazolin nitrate, Tetryzolin hydrochloride, Antazolin hydrochloride, Antazolin sulphate, Pilocarpin chloride, Vitamin A-palmitate and zinc sulphate;
b) ophthalmological buffers such as boric acid, borax, acetic acid, sodium acetate, phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium phosphate, Trometamol, citric acid and sodium citrate;
c) ophthalmological preservatives such as benzyl, alkylammonium chloride, benzoxonium chloride, chlorhexidine digluconate, chlorobutanol, phenylethyl alcohol and Thiomersal;
d) solvents such as ethanol, glycerol, polyethylene glycol and water or mixtures thereof;
e) solution aids such as Cremophor EL, Cremophor RH, Tween 20 and Tween 80;
f) isotonising agents such as sodium chloride, mannitol and sorbitol,
g) chelate formers such as disodium EDTA;
h) antioxidants such as a-tocopherol acetate, ascorbic acid, N-acetyl-cystine, sodium bisulphite, sodium thiosulphate and propyl gallate; and
i) viscosity-increasing compounds such as methylhydroxypropyl cellulose, saccharose, Carbopol 934P, Carbopol 940, Carbopol 980 and Polaxomer F127.
The cosmetic composition according to the present invention may also be used as lubricant.
The cosmetic composition of the invention may also comprise further components which are known to perform a useful function in a cosmetic composition. Examples of such further components include, e.g., emollients, skin moisturizers, UV absorbers such as an oxanilide, a triazine or triazole, additional thickening agents such as xanthan, moisture-retention agents such as glycerine, film formers, preservatives, perfumes and colourants.
The xcex2-1,3-scleroglucan component of the cosmetic composition of the present invention has three-dimensional structure of crosslinked triple helices and contains in its structure xcex2-1,3-bonded glucopyranose as the main chain and xcex2-1,6-bonded glucopyranose as side chains and has the structural formula: 
in which n is a number which provides the xcex2-1,3-scleroglucan component with a mean molecular weight (MW) of 1xc3x97106 to 12xc3x97106, preferably 2xc3x97106 to 10xc3x97106, determined from the readily measured Staudinger Index xcex7 using the following Mark-Houwink equation:
MW=[xcex7/4xc3x9745xc3x9710xe2x88x927]1/1.49.
Preferably, a 0.3 g/l aqueous solution of the xcex2-1,3-scleroglucan has a glucose content below 0.1 g/l and a viscosity of 50 to 190 mPa.s, measured at a shear rate of 0.3 sxe2x88x921 at 20xc2x0 C.
The xcex2-1,3-scleroglucan having a mean molecular weight of 1xc3x97106 to 12xc3x97106, preferably 2xc3x97106 to 10xc3x97106, and having a three-dimensional crosslinked triple helix structure is a new composition of matter and, as such, constitutes a second aspect of the present invention.
The molecular characterisation of the xcex2-1,3-scleroglucan may be conveniently conducted by light scattering techniques using different polymer concentrations in a suitable solvent such as 0.01N aqueous sodium hydroxide. For example, a stock solution may be produced from a freeze-dried, powdered xcex2-1,3-scleroglucan sample and the stock solution may then be stirred for 1-2 days at 25xc2x0 C. The static and dynamic light scattering parameters may then be determined. From these values, there may be derived the ratio (Rg/Rh) of the radius of gyration (Rg) to the hydrodynamic radius (Rh). This ratio (Rg/Rh) serves as an indication of the shape of the test sample.
Viscosity measurements may then be carried out at 25xc2x0 C. on various diluted samples of the stock solution using aqueous sodium hydroxide or dimethylsulfoxide as solvent. A suitable instrument for conducting the viscosity measurements is the Ubbelohde-Capillary|(capillary constant K=0.009693), with the application of the Hagenbach correction.
These molecular characterisation techniques demonstrate that the new xcex21,3-scleroglucan is present as physically connected triple helices at 25xc2x0 C.
The xcex2-1,3-scleroglucan is produced using the plant-pathogenic fungi imperfecti Sclerotium rolfsii ATCC 15205. This process forms a third aspect of the present invention.
The process of the invention is characterized in that microorganisms, in the form of the plant-pathogenic fungi imperfecti Sclerotium rolfsii ATCC 15205 are cultivated in a culture medium under microaerobic conditions.
The basic cultivation medium used may be that described in U.S. Pat. No. 3,301,848 comprising a carbon source; a nitrogen source such as an ammonium salt or, preferably, sodium nitrate; a phosphate source such as dipotassiumhydrogen phosphate trihydrate; potassium chloride; magnesium sulfate heptahydrate; ferric sulfate heptahydrate; and yeast extract. The use of dipotassiumhydrogen phosphate trihydrate as phosphate source has the advantage that it acidifies the medium and therefore obviates the need for a separate acid to adjust the medium to a pH value of about 2.
In a preferred embodiment, glucose is used as the carbon source. The glucose is converted to xcex2-1,3-scleroglucan, biomass, CO2 and oxalic acid, which is the only detectable by-product.
To this basic medium are preferably added citric acid hydrate, preferably in an amount ranging from 0.2 to 1.5 g/l; thiamine or a mineral acid salt thereof, preferably in an amount ranging from 0.3 to 30 mg/l; and a zinc salt such as zinc sulfate, preferably in an amount ranging from 0.3 to 30 mg/l. While the yeast extract per se is a source of both thiamine and zinc, yeast extract does not provide these ingredients in sufficient amounts to provide optimum yields of the desired xcex2-1,3-scleroglucan product.
It has been found that, by reducing the amount of oxygen used, the amounts of CO2 and biomass formed are reduced, with consequent increased formation of the desired xcex2-1,3-scleroglucan. Accordingly, it is preferred to operate the process of the present invention using a specific oxygen uptake rate (oxygen uptake rate based on the biomass) within the range of from 0.01 to 0.08 hxe2x88x921.
It is surprising that the yields of the desired xcex2-1,3-scleroglucan product are increased when the oxygen uptake rate decreases continuously during the cultivation process, so that the oxygen supply to the cells deteriorates continuously. An explanation could be that, since the organism prefers a microaerobic environment, it surrounds itself, even xe2x80x9cin vivoxe2x80x9d, with a mucous skin, which greatly inhibits the oxygen transfer. Consequently, its actual requirement for oxygen may be far less than the microaerobic oxygen supply in the reactor. This is consistent with the observed result that, on increasing the oxygen supply to the reactor, the oxygen serves to excessively consume the glucose by respiration, resulting in increased growth and decreased yield coefficient (g biomass per g of scleroglucan).
Preferably, a nitrogen-limited cultivation preculture (inoculum) is used. Surprisingly, it has been found that the use of a nitrogen-limited preculture, as inoculum in the cultivation, leads to an improved product-to-biomass ratio.
By limiting the amount of nitrogen source in the cultivation medium, the ratio of the desired xcex2-1,3-scleroglucan product to biomass is significantly greater than when cultivation is conducted using a standard inoculum. It is known that a high C/N ratio has a positive effect on the product concentration during the production of microbial polysaccharides. The present observation of the favourable effect of xe2x80x9creverse N-limitationxe2x80x9d (reverse since an N-limited inoculum culture, supplied to the medium, is subsequently not N-limited, since the medium thereafter contains a sufficient N-source) has not been previously reported. A possible explanation for the favourable effect of xe2x80x9creverse N-limitationxe2x80x9d could be that the organism, when it is N-limited, cannot fix the cell-wall polysaccharide inside the wall, due to a deficiency of chitin, which contains nitrogen as N-acetylglucosamine units. Consequently, the cell-wall polysaccharide is released into the medium to a greater extent.
Accordingly, it is preferred to operate the process of the present invention using amounts of nitrogen source in the cultivation medium ranging from 0.2 to 0.8 g N/l.
As already indicated, oxalic acid is the only detectable by-product of the process of the present invention. The drop in pH value during the cultivation process of the invention is proportional to the amount of oxalic acid formed. The xcex2-1,3,-scleroglucan product and biomass concentrations are not influenced by the initial pH value applied in the process of the invention. This observation runs counter to previous findings in which substantially impaired product and biomass formation was reported using pH values below 3. Since this pH limitation does not apply to Sclerotium rolfsii, the cultivation process according to the present invention can be operated under fully non-sterile conditions at pH 2, apart from the separate sterilization of yeast extract.
Preferably, the cultivation process according to the present invention is effected with agitation, at 15 to 40xc2x0 C.; the culture solution is then separated from the mass of cells; and the xcex2-1,3-scleroglucan product so obtained is isolated in conventional manner.
The microbial production of xcex2-1,3-scleroglucan using the Fungi imperfecti Sclerotium rolfsii ATCC 15205 is associated with the large increase in the viscosity of the medium in the reactor during the cultivation. In addition, the culture suspension shows pseudoplastic flow behaviour. The organism as well as the xcex2-1,3-scleroglucan product are sensitive to shear.
As the reactor size increases, the importance of an adequate mixing of the highly-viscous medium rises. A reduced level of mixing leads to a strong decrease in the rate of growth and polysaccharide formation during the cultivation. In order to achieve adequate mixing in large reactors, it is standard practice to operate with high stirrer speeds. In the case of scleroglucan production, however, high mean shear rates and maximum stirrer speeds in the reactor degrade the polysaccharide. It has now been found that equally good mixing can be attained, in a comparable time, using very high gasification rates. In this way, the gasification mainly takes over the task of effecting axial mixing of the medium. High gasification rates also ensure a rotation of the highly-viscous reactor volume up to the end of the cultivation. Such a less severe mixing enables the production of a higher molecular product. The stirring device effects the necessary shearing off of the polysaccharide from the cell surfaces. The mean shear rates in the reactor preferably range from 18 to 25 sxe2x88x921 and the maximum stirrer speed preferably ranges from 0.7 to 1.0 m/s. Moreover, the high proportion of gas in the liquid leads to a lowering of the density of the total system and thus to a reduction of the viscosity.